/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Cimarron D. Taylor of the University of California, Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>

#include <err.h>
#include <fts.h>
#include <stdio.h>
#include <time.h>

#include "find.h"

static PLAN *yanknode(PLAN **);
static PLAN *yankexpr(PLAN **);

/*
 * yanknode --
 *	destructively removes the top from the plan
 */
static PLAN *yanknode(PLAN **planp) {
  PLAN *node; /* top node removed from the plan */

  if ((node = (*planp)) == NULL) return (NULL);
  (*planp) = (*planp)->next;
  node->next = NULL;
  return (node);
}

/*
 * yankexpr --
 *	Removes one expression from the plan.  This is used mainly by
 *	paren_squish.  In comments below, an expression is either a
 *	simple node or a f_expr node containing a list of simple nodes.
 */
static PLAN *yankexpr(PLAN **planp) {
  PLAN *next;    /* temp node holding subexpression results */
  PLAN *node;    /* pointer to returned node or expression */
  PLAN *tail;    /* pointer to tail of subplan */
  PLAN *subplan; /* pointer to head of ( ) expression */

  /* first pull the top node from the plan */
  if ((node = yanknode(planp)) == NULL) return (NULL);

  /*
   * If the node is an '(' then we recursively slurp up expressions
   * until we find its associated ')'.  If it's a closing paren we
   * just return it and unwind our recursion; all other nodes are
   * complete expressions, so just return them.
   */
  if (node->execute == f_openparen)
    for (tail = subplan = NULL;;) {
      if ((next = yankexpr(planp)) == NULL) errx(1, "(: missing closing ')'");
      /*
       * If we find a closing ')' we store the collected
       * subplan in our '(' node and convert the node to
       * a f_expr.  The ')' we found is ignored.  Otherwise,
       * we just continue to add whatever we get to our
       * subplan.
       */
      if (next->execute == f_closeparen) {
        if (subplan == NULL) errx(1, "(): empty inner expression");
        node->p_data[0] = subplan;
        node->execute = f_expr;
        break;
      } else {
        if (subplan == NULL)
          tail = subplan = next;
        else {
          tail->next = next;
          tail = next;
        }
        tail->next = NULL;
      }
    }
  return (node);
}

/*
 * paren_squish --
 *	replaces "parenthesized" plans in our search plan with "expr" nodes.
 */
PLAN *paren_squish(PLAN *plan) {
  PLAN *expr;   /* pointer to next expression */
  PLAN *tail;   /* pointer to tail of result plan */
  PLAN *result; /* pointer to head of result plan */

  result = tail = NULL;

  /*
   * the basic idea is to have yankexpr do all our work and just
   * collect its results together.
   */
  while ((expr = yankexpr(&plan)) != NULL) {
    /*
     * if we find an unclaimed ')' it means there is a missing
     * '(' someplace.
     */
    if (expr->execute == f_closeparen) errx(1, "): no beginning '('");

    /* add the expression to our result plan */
    if (result == NULL)
      tail = result = expr;
    else {
      tail->next = expr;
      tail = expr;
    }
    tail->next = NULL;
  }
  return (result);
}

/*
 * not_squish --
 *	compresses "!" expressions in our search plan.
 */
PLAN *not_squish(PLAN *plan) {
  PLAN *next;   /* next node being processed */
  PLAN *node;   /* temporary node used in f_not processing */
  PLAN *tail;   /* pointer to tail of result plan */
  PLAN *result; /* pointer to head of result plan */

  tail = result = NULL;

  while ((next = yanknode(&plan))) {
    /*
     * if we encounter a ( expression ) then look for nots in
     * the expr subplan.
     */
    if (next->execute == f_expr) next->p_data[0] = not_squish(next->p_data[0]);

    /*
     * if we encounter a not, then snag the next node and place
     * it in the not's subplan.  As an optimization we compress
     * several not's to zero or one not.
     */
    if (next->execute == f_not) {
      int notlevel = 1;

      node = yanknode(&plan);
      while (node != NULL && node->execute == f_not) {
        ++notlevel;
        node = yanknode(&plan);
      }
      if (node == NULL) errx(1, "!: no following expression");
      if (node->execute == f_or) errx(1, "!: nothing between ! and -o");
      /*
       * If we encounter ! ( expr ) then look for nots in
       * the expr subplan.
       */
      if (node->execute == f_expr)
        node->p_data[0] = not_squish(node->p_data[0]);
      if (notlevel % 2 != 1)
        next = node;
      else
        next->p_data[0] = node;
    }

    /* add the node to our result plan */
    if (result == NULL)
      tail = result = next;
    else {
      tail->next = next;
      tail = next;
    }
    tail->next = NULL;
  }
  return (result);
}

/*
 * or_squish --
 *	compresses -o expressions in our search plan.
 */
PLAN *or_squish(PLAN *plan) {
  PLAN *next;   /* next node being processed */
  PLAN *tail;   /* pointer to tail of result plan */
  PLAN *result; /* pointer to head of result plan */

  tail = result = next = NULL;

  while ((next = yanknode(&plan)) != NULL) {
    /*
     * if we encounter a ( expression ) then look for or's in
     * the expr subplan.
     */
    if (next->execute == f_expr) next->p_data[0] = or_squish(next->p_data[0]);

    /* if we encounter a not then look for or's in the subplan */
    if (next->execute == f_not) next->p_data[0] = or_squish(next->p_data[0]);

    /*
     * if we encounter an or, then place our collected plan in the
     * or's first subplan and then recursively collect the
     * remaining stuff into the second subplan and return the or.
     */
    if (next->execute == f_or) {
      if (result == NULL) errx(1, "-o: no expression before -o");
      next->p_data[0] = result;
      next->p_data[1] = or_squish(plan);
      if (next->p_data[1] == NULL) errx(1, "-o: no expression after -o");
      return (next);
    }

    /* add the node to our result plan */
    if (result == NULL)
      tail = result = next;
    else {
      tail->next = next;
      tail = next;
    }
    tail->next = NULL;
  }
  return (result);
}
